1. Field of the Invention
This invention relates to a waterproof camera having a waterproof seal provided between the outer box and a back plate of the camera, and is especially constructed to prevent the infiltration into the camera of water remaining behind the waterproof seal.
2. Description of Related Art
FIG. 6 is a cross-sectional view of a conventional type waterproof camera. FIG. 7 is an enlarged view showing the waterproof seal of the conventional waterproof camera.
As shown in FIG. 6, the camera mechanism 25 is received into the outer box 22, after which it is enclosed by the back plate 23. A cover 26 is provided to cover a gap 22b that is present between the outer box 22 and the camera mechanism 25. Cover 26 prevents gap 22b from being visible from the photographer side (the right side in FIG. 6) of the camera. A resilient material 26a seals the radially outer portion of cover 26 to the outer box 22. The radially inner portion of cover 26, which is defined by flat surface 26b of cover 26, defines an aperture through which the rear portion of camera mechanism 25 may be accessed.
As shown in FIG. 7, a waterproof seal is formed by the resilient force of an O-ring 24, which is inserted into the seal groove 23a of the back plate 23, and contacts the seal wall 22a of the outer box 22. A waterproof glass 28 also is provided and is fitted into the front surface (left side of FIG. 6) of the outer box 22. An O-ring 29 is located between the outer box 22 and the waterproof glass 28. With this type of waterproof seal construction, infiltration of water into the interior of the camera is prevented and the camera mechanism 25 and photographic lens 27 accommodated within the outer box 22 is protected from water.
With the conventional type of waterproof cameras described above, when water pressure increases, the water infiltrates and remains in the gap 31a up to the seal wall 22a of the O-ring 24 and in the gap 31b between the back plate 23 and the outer box 22, as shown in FIG. 7. Even if wiped away from the outside, water remains in the gaps 31a, 31b and cannot be evacuated easily when the back plate 23 is in the closed position. When the back plate 23 is opened, the trapped water travels along the seal wall 22a and forms water droplets on the flat surface 26b of the cover 26. Furthermore, the problem exists that water seeps into the interior past the aperture of cover 26, causing corrosion of the camera mechanism 25 and making it inoperable.